The leakage, while radioactive, has been captured inside the plant’s containment structure and will end up processed by systems designed to handle such liquids, said NRC spokesman Neil Sheehan and the nuclear plant’s operator Talen Energy Corp. There is no danger to plant workers or the public, Sheehan said.

Susquehanna operators began the process of powering down the reactor late Sunday, Talen officials said.

“Our nuclear professionals have spent the past week developing various contingencies to ensure the safest and most efficient approach to repairing the leak,” said Jon Franke, site vice president.

The company did not say when it expects to return Unit 1 to service. Susquehanna Unit 2 continues to operate at full power.

Unit 1 shut down about a week in November due to a leak discovered during routine equipment testing.

The Susquehanna plant is in Salem Township, Luzerne County, about 75 miles northwest of Allentown. Susquehanna Nuclear LLC and Allegheny Electric Cooperative Inc. jointly own the facility.